Dual‐Wavelength Comparative Imaging Based on a Novel NIR‐II/IIb Emissive Rare Earth‐Doped Nanoparticle

Abstract The second near‐infrared biological window two (NIR‐II, 1000–1700 nm) imaging has made remarkable achievements in fluorescence imaging of diseases. Here, this work takes advantage of the rich spectral properties of rare‐earth doped nanoparticles (RENPs) and their capability to present multiple emission peaks in different luminescence regions simultaneously; novel RENPs are synthesized that have emission peaks in the NIR‐II_1000nm (1000–1300 nm) region and enhanced emission in the NIR‐IIb (1500–1700 nm) window and are named as NEU‐RENPs. These RENPs with new compositions enable a fair comparison to evaluate their imaging performance in NIR‐II_1000nm and NIR‐IIb regions under the same conditions. The imaging abilities of the resulted nanoparticles in NIR‐II_{1000 nm} and NIR‐IIb regions are investigated systematically for local blood vessels, tumor vessels, acute inflammatory vessels, arterial thrombosis, cerebrovascular inflammation, and brain injury models. The results indicate that imaging of NIR‐IIb shows higher resolution and sensitivity than that of NIR‐II_1000nm, and it has a stronger ability to accurately distinguish normal and pathological tissues. Interestingly, the fuzzy image of NIR‐II_1000nm reveals more information about the background structure of the target, which is difficult to be achieved in NIR‐IIb imaging. The results prove NEU‐RENPs based NIR‐IIb imaging is preferable for biomedical applications.